Took delivery on my new custom Ti gravel frame on Sunday. Wrapping up the build. Never tried to hide it from the future spouse. I defused her by telling her she was getting the next killer bike – a carbon full-squish. Bringing that home at bonus time this year.
You already are winning due to your significant other riding bikes. 
But just a heads up… dating/engagement is a whole different life compared to post nuptials. Not worse… just different. Be prepared! 
“Everyone on the Trainerroad forum told me I need a new bike. It wasn’t me. Blame them.”
Can confirm. It was all me.
Don’t I know it. This isn’t my first…or second 
…rodeo. First only where I’m married to a bike addict, though.